function sys = boost_sys(domain, fc, A)

% init
if strcmp(domain{1}, "s")
    
elseif strcmp(domain{1}, "z")
    Ts = domain{2};
end


% design
wc = 2*pi*fc;

if A >= 1
    % BoostUp
    wz = wc;
    wp = wc ./ A;
elseif A < 1
    % BoostDown
    wz = wc .* A;
    wp = wc;
end

s = tf("s");
sys_s = (s+wz)/(s+wp);


% output
if strcmp(domain{1}, "s")
    sys = sys_s;
elseif strcmp(domain{1}, "z")
    sys_z = c2d(sys_s, Ts, 'tustin');
    sys = sys_z;
end

end